The essentials in 30 seconds
Woodworm is the larva of a wood-boring beetle, most often the common furniture beetle (Anobium punctatum). The larvae live inside the wood for years; what you see are the round exit holes, 1–2 mm across, and the fine dust (frass) that falls from them. Fresh, sharp-edged holes with pale dust mean an active infestation; dark holes with no new dust are usually old. Furniture can be treated by injecting woodworm fluid into the holes and brushing it over bare wood. Beams, joists and floorboards need a specialist survey.
- Fresh pale dust under a piece = active woodworm.
- Old, dark holes with no dust may be from an infestation that ended long ago.
- Damp wood attracts woodworm: drying it out is part of the cure.
What woodworm is
The common furniture beetle lays its eggs in cracks and pores in the wood. The larvae tunnel inside for several years, then turn into adults and bore their way out, leaving the exit holes. Other species exist, such as the house longhorn beetle, which attacks softwood roof timbers and leaves larger oval holes, and the deathwatch beetle, typical of old damp hardwood beams. Termites are not woodworm but also eat wood: read our termites guide if you see mud tubes.
How to tell if woodworm is active
- New exit holes: sharp edges and the inside the colour of freshly cut wood.
- Fresh frass: fine, pale dust below the piece or spilling from the holes.
- Soft wood: an awl sinks in or the wood crumbles.
- Beetles: small brown beetles near windows in spring and summer.
To check, vacuum the dust, put dark paper under the piece and look again after a few weeks. If you are still unsure, monitor for a year: new holes or dust mean it is active. Many holes are years old, sometimes from before the wood was even cut.
Woodworm or termites
| Feature | Woodworm | Termites |
|---|---|---|
| Visible sign | Exit holes and fine dust | No exit holes; hidden galleries and crumbling wood |
| Galleries | Packed with dust | Clean, with soil or mud |
| Where | Furniture, joists, frames, floorboards | Wood in contact with damp or soil |
| Speed | Slow, over years | Can be fast and reach the structure |
| Treatment | Woodworm fluid in the affected piece | Professional treatment of the building |
How to treat woodworm in furniture step by step
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01
Isolate the piece
Move it away from other wooden furniture if you can.
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02
Clean and inspect
Vacuum the dust and find every hole. Mark the worst areas.
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03
Treat bare wood
Fluid soaks into unfinished wood; on varnished or waxed pieces, treat the unfinished parts (backs, insides, legs) and the holes themselves.
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04
Inject the holes
Use the product's nozzle or a syringe to inject fluid into the holes, working from the bottom up.
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05
Brush the surfaces
Apply two or three coats to unfinished surfaces, letting each dry as the label says.
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06
Fill and watch
Once dry, fill the holes with wax or wood filler. New holes later will show if it is still active.
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07
Repeat if needed
If new holes appear next spring, treat again.
Woodworm in beams, joists and floorboards
In beams, joists, roof timbers or floors, the question is not only killing the larvae but whether the wood still has its strength. A specialist surveyor checks how much sound timber is left and recommends the treatment, consolidation or replacement. Call a specialist if:
- The affected timber is structural: beams, joists, rafters or posts.
- There are new cracks, sagging or creaking.
- Dust falls from ceilings or under timber floors.
- You suspect termites.
- You live in a block of flats: shared timber is treated by agreement of the owners.
Avoid paying for chemical treatment of old, inactive holes: drying the building and monitoring is often enough.
How to keep woodworm away
- Control damp: damp wood is far more attractive to beetles. Ventilate lofts and cellars and fix leaks.
- Protect new or restored wood with a preventive treatment before varnishing or painting.
- Check second-hand furniture for fresh holes and dust before bringing it home.
- Keep surfaces finished: bare wood, cracks and gaps are where eggs are laid.
- Check each spring any piece that has had woodworm before.
Woodworm: frequently asked questions
How do I know if woodworm is active?
Fresh, sharp-edged holes with pale wood inside and fine dust below the piece. Old holes are dark and dusty.
Can I treat woodworm myself?
In furniture, yes, with an authorised woodworm fluid. Structural timber needs a specialist.
Is woodworm in floorboards serious?
It can be if the boards or joists lose strength. Ask a specialist to check.
Does woodworm spread to other furniture?
It can, which is why you move the piece away and treat it promptly.
Do old holes need treatment?
Not if they are inactive. Monitor for new holes and dust before treating.
What causes woodworm?
Beetles lay eggs in wood, especially damp or unfinished wood. Controlling damp helps prevent it.
Sources
Museum and building conservation guidance, checked on 24 October 2026.
- Natural History Museum · Furniture beetle identification guide ↗The common furniture beetle and its signs.
- SPAB · Wood-boring insects ↗Active versus old holes, monitoring for a year, damp as a cause and avoiding unnecessary treatment.
- US EPA · Dos and don'ts of pest control ↗Safe use of pesticides at home.
Found fresh dust?
Photograph the holes and dust and note which pieces or rooms are affected before you ask a specialist.